/*
 * jdapistd.c
 *
 * Copyright (C) 1994-1995, Thomas G. Lane.
 * This file is part of the Independent JPEG Group's software.
 * For conditions of distribution and use, see the accompanying README file.
 *
 * This file contains application interface code for the decompression half
 * of the JPEG library.  These are the "standard" API routines that are
 * used in the normal full-decompression case.  They are not used by a
 * transcoding-only application.  Note that if an application links in
 * jpeg_start_decompress, it will end up linking in the entire decompressor.
 * We thus must separate this file from jdapimin.c to avoid linking the
 * whole decompression library into a transcoder.
 */

#define JPEG_INTERNALS
#include "jinclude.h"
#include "jpeglib.h"


/* Forward declarations */
LOCAL boolean output_pass_setup JPP( (j_decompress_ptr cinfo) );


/*
 * Decompression initialization.
 * jpeg_read_header must be completed before calling this.
 *
 * If a multipass operating mode was selected, this will do all but the
 * last pass, and thus may take a great deal of time.
 *
 * Returns FALSE if suspended.  The return value need be inspected only if
 * a suspending data source is used.
 */

GLOBAL boolean
jpeg_start_decompress( j_decompress_ptr cinfo ) {
    if ( cinfo->global_state == DSTATE_READY ) {
        /* First call: initialize master control, select active modules */
        jinit_master_decompress( cinfo );
        if ( cinfo->buffered_image ) {
            /* No more work here; expecting jpeg_start_output next */
            cinfo->global_state = DSTATE_BUFIMAGE;
            return TRUE;
        }
        cinfo->global_state = DSTATE_PRELOAD;
    }
    if ( cinfo->global_state == DSTATE_PRELOAD ) {
        /* If file has multiple scans, absorb them all into the coef buffer */
        if ( cinfo->inputctl->has_multiple_scans ) {
#ifdef D_MULTISCAN_FILES_SUPPORTED
            for (;; ) {
                int retcode;
                /* Call progress monitor hook if present */
                if ( cinfo->progress != NULL ) {
                    ( *cinfo->progress->progress_monitor )( (j_common_ptr) cinfo );
                }
                /* Absorb some more input */
                retcode = ( *cinfo->inputctl->consume_input )( cinfo );
                if ( retcode == JPEG_SUSPENDED ) {
                    return FALSE;
                }
                if ( retcode == JPEG_REACHED_EOI ) {
                    break;
                }
                /* Advance progress counter if appropriate */
                if ( ( cinfo->progress != NULL ) &&
                    ( ( retcode == JPEG_ROW_COMPLETED ) || ( retcode == JPEG_REACHED_SOS ) ) ) {
                    if ( ++cinfo->progress->pass_counter >= cinfo->progress->pass_limit ) {
                        /* jdmaster underestimated number of scans; ratchet up one scan */
                        cinfo->progress->pass_limit += (long) cinfo->total_iMCU_rows;
                    }
                }
            }
#else
            ERREXIT( cinfo, JERR_NOT_COMPILED );
#endif /* D_MULTISCAN_FILES_SUPPORTED */
        }
        cinfo->output_scan_number = cinfo->input_scan_number;
    } else if ( cinfo->global_state != DSTATE_PRESCAN ) {
        ERREXIT1( cinfo, JERR_BAD_STATE, cinfo->global_state );
    }
    /* Perform any dummy output passes, and set up for the final pass */
    return output_pass_setup( cinfo );
}


/*
 * Set up for an output pass, and perform any dummy pass(es) needed.
 * Common subroutine for jpeg_start_decompress and jpeg_start_output.
 * Entry: global_state = DSTATE_PRESCAN only if previously suspended.
 * Exit: If done, returns TRUE and sets global_state for proper output mode.
 *       If suspended, returns FALSE and sets global_state = DSTATE_PRESCAN.
 */

LOCAL boolean
output_pass_setup( j_decompress_ptr cinfo ) {
    if ( cinfo->global_state != DSTATE_PRESCAN ) {
        /* First call: do pass setup */
        ( *cinfo->master->prepare_for_output_pass )( cinfo );
        cinfo->output_scanline = 0;
        cinfo->global_state = DSTATE_PRESCAN;
    }
    /* Loop over any required dummy passes */
    while ( cinfo->master->is_dummy_pass ) {
#ifdef QUANT_2PASS_SUPPORTED
        /* Crank through the dummy pass */
        while ( cinfo->output_scanline < cinfo->output_height ) {
            JDIMENSION last_scanline;
            /* Call progress monitor hook if present */
            if ( cinfo->progress != NULL ) {
                cinfo->progress->pass_counter = (long) cinfo->output_scanline;
                cinfo->progress->pass_limit = (long) cinfo->output_height;
                ( *cinfo->progress->progress_monitor )( (j_common_ptr) cinfo );
            }
            /* Process some data */
            last_scanline = cinfo->output_scanline;
            ( *cinfo->main->process_data )( cinfo, (JSAMPARRAY) NULL,
                                            &cinfo->output_scanline, (JDIMENSION) 0 );
            if ( cinfo->output_scanline == last_scanline ) {
                return FALSE;
            }           /* No progress made, must suspend */
        }
        /* Finish up dummy pass, and set up for another one */
        ( *cinfo->master->finish_output_pass )( cinfo );
        ( *cinfo->master->prepare_for_output_pass )( cinfo );
        cinfo->output_scanline = 0;
#else
        ERREXIT( cinfo, JERR_NOT_COMPILED );
#endif /* QUANT_2PASS_SUPPORTED */
    }
    /* Ready for application to drive output pass through
     * jpeg_read_scanlines or jpeg_read_raw_data.
     */
    cinfo->global_state = cinfo->raw_data_out ? DSTATE_RAW_OK : DSTATE_SCANNING;
    return TRUE;
}


/*
 * Read some scanlines of data from the JPEG decompressor.
 *
 * The return value will be the number of lines actually read.
 * This may be less than the number requested in several cases,
 * including bottom of image, data source suspension, and operating
 * modes that emit multiple scanlines at a time.
 *
 * Note: we warn about excess calls to jpeg_read_scanlines() since
 * this likely signals an application programmer error.  However,
 * an oversize buffer (max_lines > scanlines remaining) is not an error.
 */

GLOBAL JDIMENSION
jpeg_read_scanlines( j_decompress_ptr cinfo, JSAMPARRAY scanlines,
                     JDIMENSION max_lines ) {
    JDIMENSION row_ctr;

    if ( cinfo->global_state != DSTATE_SCANNING ) {
        ERREXIT1( cinfo, JERR_BAD_STATE, cinfo->global_state );
    }
    if ( cinfo->output_scanline >= cinfo->output_height ) {
        WARNMS( cinfo, JWRN_TOO_MUCH_DATA );
        return 0;
    }

    /* Call progress monitor hook if present */
    if ( cinfo->progress != NULL ) {
        cinfo->progress->pass_counter = (long) cinfo->output_scanline;
        cinfo->progress->pass_limit = (long) cinfo->output_height;
        ( *cinfo->progress->progress_monitor )( (j_common_ptr) cinfo );
    }

    /* Process some data */
    row_ctr = 0;
    ( *cinfo->main->process_data )( cinfo, scanlines, &row_ctr, max_lines );
    cinfo->output_scanline += row_ctr;
    return row_ctr;
}


/*
 * Alternate entry point to read raw data.
 * Processes exactly one iMCU row per call, unless suspended.
 */

GLOBAL JDIMENSION
jpeg_read_raw_data( j_decompress_ptr cinfo, JSAMPIMAGE data,
                    JDIMENSION max_lines ) {
    JDIMENSION lines_per_iMCU_row;

    if ( cinfo->global_state != DSTATE_RAW_OK ) {
        ERREXIT1( cinfo, JERR_BAD_STATE, cinfo->global_state );
    }
    if ( cinfo->output_scanline >= cinfo->output_height ) {
        WARNMS( cinfo, JWRN_TOO_MUCH_DATA );
        return 0;
    }

    /* Call progress monitor hook if present */
    if ( cinfo->progress != NULL ) {
        cinfo->progress->pass_counter = (long) cinfo->output_scanline;
        cinfo->progress->pass_limit = (long) cinfo->output_height;
        ( *cinfo->progress->progress_monitor )( (j_common_ptr) cinfo );
    }

    /* Verify that at least one iMCU row can be returned. */
    lines_per_iMCU_row = cinfo->max_v_samp_factor * cinfo->min_DCT_scaled_size;
    if ( max_lines < lines_per_iMCU_row ) {
        ERREXIT( cinfo, JERR_BUFFER_SIZE );
    }

    /* Decompress directly into user's buffer. */
    if ( !( *cinfo->coef->decompress_data )( cinfo, data ) ) {
        return 0;
    }                   /* suspension forced, can do nothing more */

    /* OK, we processed one iMCU row. */
    cinfo->output_scanline += lines_per_iMCU_row;
    return lines_per_iMCU_row;
}


/* Additional entry points for buffered-image mode. */

#ifdef D_MULTISCAN_FILES_SUPPORTED

/*
 * Initialize for an output pass in buffered-image mode.
 */

GLOBAL boolean
jpeg_start_output( j_decompress_ptr cinfo, int scan_number ) {
    if ( ( cinfo->global_state != DSTATE_BUFIMAGE ) &&
        ( cinfo->global_state != DSTATE_PRESCAN ) ) {
        ERREXIT1( cinfo, JERR_BAD_STATE, cinfo->global_state );
    }
    /* Limit scan number to valid range */
    if ( scan_number <= 0 ) {
        scan_number = 1;
    }
    if ( ( cinfo->inputctl->eoi_reached ) &&
        ( scan_number > cinfo->input_scan_number ) ) {
        scan_number = cinfo->input_scan_number;
    }
    cinfo->output_scan_number = scan_number;
    /* Perform any dummy output passes, and set up for the real pass */
    return output_pass_setup( cinfo );
}


/*
 * Finish up after an output pass in buffered-image mode.
 *
 * Returns FALSE if suspended.  The return value need be inspected only if
 * a suspending data source is used.
 */

GLOBAL boolean
jpeg_finish_output( j_decompress_ptr cinfo ) {
    if ( ( ( cinfo->global_state == DSTATE_SCANNING ) ||
          ( cinfo->global_state == DSTATE_RAW_OK ) && cinfo->buffered_image ) ) {
        /* Terminate this pass. */
        /* We do not require the whole pass to have been completed. */
        ( *cinfo->master->finish_output_pass )( cinfo );
        cinfo->global_state = DSTATE_BUFPOST;
    } else if ( cinfo->global_state != DSTATE_BUFPOST ) {
        /* BUFPOST = repeat call after a suspension, anything else is error */
        ERREXIT1( cinfo, JERR_BAD_STATE, cinfo->global_state );
    }
    /* Read markers looking for SOS or EOI */
    while ( cinfo->input_scan_number <= cinfo->output_scan_number &&
            !cinfo->inputctl->eoi_reached ) {
        if ( ( *cinfo->inputctl->consume_input )( cinfo ) == JPEG_SUSPENDED ) {
            return FALSE;
        }               /* Suspend, come back later */
    }
    cinfo->global_state = DSTATE_BUFIMAGE;
    return TRUE;
}

#endif /* D_MULTISCAN_FILES_SUPPORTED */
